8205
E-31-
pH CONTROLLER 8205
5 MAINTENANCE
!
Fig. 5.1 Replacement of pH electrode
5.2 Storing and Cleaning of the Electrode
When not in operation, the electrode should be stored in a 3 molar potassium chloride
solution (223,6 g/l), providing a regenerative effect. Is there no such solution available,
normal tap water will also do for short measuring interruptions of max. 2 - 3 days. The
electrode must not be stored in distilled or deionisized water, which may be used for
rinsing purposes only!
Experience has shown, that the majority of failures in pH electrode measurements and
long response times originate from contaminated electrodes or diaphragms. Since the
contamination is subject to the application, there is no general detergent available yet.
The following detergents, however, can be recommended for most application cases:
-Greasy or oily deposits must be removed with a tenside-containing agent.
-Chalky deposits and metal hydroxide layers require diluted hydrochloric acid (10%).
-Sulphide-containing deposits (purification systems) are removed with a detergent mixture
of diluted hydrochloric acid (10%) and saturated pepsin.
-For very slow pH-electrodes dip the electrode for 1 minute into a 2% HF and 5% HCL
solution and rinse thoroughly.
Observe safety regulations, when handling acid-containing solutions. Always rinse
electrode with deionisized water and leave for approx. 10 minutes in a 3 molar
potassium chloride solution or in tap water.
!
1. Disconnect supply voltage and
make sure that there is no pressure
on pipe or tank.
2.Remove the controller from the pipe or
submersion assembly.
3.Unscrew the cover and open it slightly.
4.Pull out connectors
and
.
5.Pull sensor assembly
out of the
enclosure.
6. Screw electrode out of assembly
with
SW17 wrench.
7.Screw new electrode into assembly and
tighten with SW17 wrench. Reassemble
in reverse order.
Torque of the electrode 2 N.m
